diff --git a/bootstrap/unix-44/SYSTEM.h b/bootstrap/unix-44/SYSTEM.h
index 75a0aa52..d9e1f6fb 100644
--- a/bootstrap/unix-44/SYSTEM.h
+++ b/bootstrap/unix-44/SYSTEM.h
@@ -16,16 +16,18 @@ typedef unsigned short int   SYSTEM_CARD16;
 typedef signed char          SYSTEM_INT8;
 typedef unsigned char        SYSTEM_CARD8;
 
-#if (__SIZEOF_POINTER__ == 8)
+#if (__SIZEOF_POINTER__ == 8) || defined(_WIN64)
   #if defined(_WIN64)
-    typedef unsigned long long SYSTEM_ADDRESS;
+    typedef unsigned long long size_t;
   #else
-    typedef unsigned long      SYSTEM_ADDRESS;
+    typedef unsigned long      size_t;
   #endif
 #else
-  typedef unsigned int         SYSTEM_ADDRESS;
+  typedef unsigned int         size_t;
 #endif
 
+#define SYSTEM_ADDRESS size_t
+#define _SIZE_T_DECLARED // For FreeBSD and OpenBSD:
 
 void *memcpy(void *dest, const void *source, SYSTEM_ADDRESS size);
 
diff --git a/bootstrap/unix-48/SYSTEM.h b/bootstrap/unix-48/SYSTEM.h
index 75a0aa52..d9e1f6fb 100644
--- a/bootstrap/unix-48/SYSTEM.h
+++ b/bootstrap/unix-48/SYSTEM.h
@@ -16,16 +16,18 @@ typedef unsigned short int   SYSTEM_CARD16;
 typedef signed char          SYSTEM_INT8;
 typedef unsigned char        SYSTEM_CARD8;
 
-#if (__SIZEOF_POINTER__ == 8)
+#if (__SIZEOF_POINTER__ == 8) || defined(_WIN64)
   #if defined(_WIN64)
-    typedef unsigned long long SYSTEM_ADDRESS;
+    typedef unsigned long long size_t;
   #else
-    typedef unsigned long      SYSTEM_ADDRESS;
+    typedef unsigned long      size_t;
   #endif
 #else
-  typedef unsigned int         SYSTEM_ADDRESS;
+  typedef unsigned int         size_t;
 #endif
 
+#define SYSTEM_ADDRESS size_t
+#define _SIZE_T_DECLARED // For FreeBSD and OpenBSD:
 
 void *memcpy(void *dest, const void *source, SYSTEM_ADDRESS size);
 
diff --git a/bootstrap/unix-88/SYSTEM.h b/bootstrap/unix-88/SYSTEM.h
index 75a0aa52..d9e1f6fb 100644
--- a/bootstrap/unix-88/SYSTEM.h
+++ b/bootstrap/unix-88/SYSTEM.h
@@ -16,16 +16,18 @@ typedef unsigned short int   SYSTEM_CARD16;
 typedef signed char          SYSTEM_INT8;
 typedef unsigned char        SYSTEM_CARD8;
 
-#if (__SIZEOF_POINTER__ == 8)
+#if (__SIZEOF_POINTER__ == 8) || defined(_WIN64)
   #if defined(_WIN64)
-    typedef unsigned long long SYSTEM_ADDRESS;
+    typedef unsigned long long size_t;
   #else
-    typedef unsigned long      SYSTEM_ADDRESS;
+    typedef unsigned long      size_t;
   #endif
 #else
-  typedef unsigned int         SYSTEM_ADDRESS;
+  typedef unsigned int         size_t;
 #endif
 
+#define SYSTEM_ADDRESS size_t
+#define _SIZE_T_DECLARED // For FreeBSD and OpenBSD:
 
 void *memcpy(void *dest, const void *source, SYSTEM_ADDRESS size);
 
diff --git a/bootstrap/windows-48/SYSTEM.h b/bootstrap/windows-48/SYSTEM.h
index 75a0aa52..d9e1f6fb 100644
--- a/bootstrap/windows-48/SYSTEM.h
+++ b/bootstrap/windows-48/SYSTEM.h
@@ -16,16 +16,18 @@ typedef unsigned short int   SYSTEM_CARD16;
 typedef signed char          SYSTEM_INT8;
 typedef unsigned char        SYSTEM_CARD8;
 
-#if (__SIZEOF_POINTER__ == 8)
+#if (__SIZEOF_POINTER__ == 8) || defined(_WIN64)
   #if defined(_WIN64)
-    typedef unsigned long long SYSTEM_ADDRESS;
+    typedef unsigned long long size_t;
   #else
-    typedef unsigned long      SYSTEM_ADDRESS;
+    typedef unsigned long      size_t;
   #endif
 #else
-  typedef unsigned int         SYSTEM_ADDRESS;
+  typedef unsigned int         size_t;
 #endif
 
+#define SYSTEM_ADDRESS size_t
+#define _SIZE_T_DECLARED // For FreeBSD and OpenBSD:
 
 void *memcpy(void *dest, const void *source, SYSTEM_ADDRESS size);
 
diff --git a/bootstrap/windows-88/SYSTEM.h b/bootstrap/windows-88/SYSTEM.h
index 75a0aa52..d9e1f6fb 100644
--- a/bootstrap/windows-88/SYSTEM.h
+++ b/bootstrap/windows-88/SYSTEM.h
@@ -16,16 +16,18 @@ typedef unsigned short int   SYSTEM_CARD16;
 typedef signed char          SYSTEM_INT8;
 typedef unsigned char        SYSTEM_CARD8;
 
-#if (__SIZEOF_POINTER__ == 8)
+#if (__SIZEOF_POINTER__ == 8) || defined(_WIN64)
   #if defined(_WIN64)
-    typedef unsigned long long SYSTEM_ADDRESS;
+    typedef unsigned long long size_t;
   #else
-    typedef unsigned long      SYSTEM_ADDRESS;
+    typedef unsigned long      size_t;
   #endif
 #else
-  typedef unsigned int         SYSTEM_ADDRESS;
+  typedef unsigned int         size_t;
 #endif
 
+#define SYSTEM_ADDRESS size_t
+#define _SIZE_T_DECLARED // For FreeBSD and OpenBSD:
 
 void *memcpy(void *dest, const void *source, SYSTEM_ADDRESS size);
 
diff --git a/src/system/SYSTEM.h b/src/system/SYSTEM.h
index fc959e63..d9e1f6fb 100644
--- a/src/system/SYSTEM.h
+++ b/src/system/SYSTEM.h
@@ -16,7 +16,7 @@ typedef unsigned short int   SYSTEM_CARD16;
 typedef signed char          SYSTEM_INT8;
 typedef unsigned char        SYSTEM_CARD8;
 
-#if (__SIZEOF_POINTER__ == 8)
+#if (__SIZEOF_POINTER__ == 8) || defined(_WIN64)
   #if defined(_WIN64)
     typedef unsigned long long size_t;
   #else
diff --git a/src/tools/make/configure.c b/src/tools/make/configure.c
index 6477943b..5bf3af68 100644
--- a/src/tools/make/configure.c
+++ b/src/tools/make/configure.c
@@ -407,7 +407,7 @@ void writeConfigurationMod() {
   fprintf(fd, "  installdir*  = '%s';\n", installdir);
   fprintf(fd, "  staticLink*  = '%s';\n", staticlink);
   fprintf(fd, "VAR\n");
-  fprintf(fd, "  versionLong-: ARRAY %d OF CHAR;\n", strnlen(versionstring, 100)+1);
+  fprintf(fd, "  versionLong-: ARRAY %zd OF CHAR;\n", strnlen(versionstring, 100)+1);
   fprintf(fd, "BEGIN\n");
   fprintf(fd, "  versionLong := '%s';\n", versionstring);
   fprintf(fd, "END Configuration.\n");